Fozzy-
Have these people owned and/or ridden in both back-to-back? I'm curious since the spring rates that come with the V1's are too low for performance, and the natural frequencies are almost dead even front to rear. This means ride settling, pitch, and oscillation will be way off. There are plenty that enjoy the Bilstein/Eibach ride. Search around. My guess is there is quite a bit of buyer's rationalization (the same reason every tune owner thinks their particular tune is the best).
"Ride comfort" is usually felt as the proper pairing of spring rates and shock valving. This is why the AST owners can run 400/800 rates and the ride is felt as "smoother" than H&R's on stock shocks. V1's are valved for their matched springs, just like Bilsteins are valved to match the stock springs, and accordingly, the eibach springs. "Ride comfort" will likely be the same, but the car will oscillate poorly with the V1's. Your passengers will pick up a feeling of queasiness.
That being said, neither of these are performance oriented suspension setups. They are best for the DD that likes to take onramps a little quicker.
Lenaxia-
I agree. I'm hesitant to buy anything, from any provider, if they aren't willing spill the details.
The B8/Swift combo was something that I was hoping would work out. The swift website shows that they are R&D'ing some lowering springs. Those haven't been released, yet. The other route was using the B8's with a coilover sleeve and 2.5" ID Swift springs. This is popular with the miata and supra guys. I recently talked to Bilstein and they said there was no way that that would work for these cars.
The damper data isn't important to the load transfer worksheet. If you work with shops/people that know what they are doing, than they will do that hard work for you. The intricacies of damper valving is waaaaaay beyond my understanding.
If you want to increase your basic knowledge of what to look for in valving charts, read these:
http://www.optimumg.com/OptimumGWebS.../TechTips.html
http://farnorthracing.com/autocross_secrets6.html
As far as "the magic number", that is a baseline recommendation by Milliken. It basically means that more of the roll gradient is taken by the front of the car. This will read as neutral to the driver. Around 5% is the rough goal. From there, changes can be made to suit the driver's needs. For example, some autocross drivers love tail-happy cars. They will usually have a magic number of 0%, or so.
For the average driving enthusiast, this magic number range will lead to a more than capable car. Who here can say that they can wring every last drop of performance out of an e90 M3? I know I can't!